The research is aimed at understanding the course of development of problem behavior and of the factors conducing to it in youth from age 12 to 22. Problem behavior includes drug use, sex behavior, aggression, and social activism in school, but focuses especially on drinking and problem drinking. Personality factors (e.g., the perception of limited opportunity, value on independence, and alienation), perceived environment (e.g., school status, peer support, and parental controls), and socialization processes (e.g., exposure to models) will be related to the occurrence and maintenance of problem behavior. The research design is longitudinal and began in 1969 with samples in every grade from 7th through freshman year in college; these samples are being followed over a period of four years. Longitudinal data will enable us to chart the "growth" of problem beavior from an age (12) when it is relatively infrequent to an age (22) by which patterns of problem behavior may have become relatively stable. The data will also enable a description of personality and social-psychological change during adolescence. Finally, attempts will be made to predict the onset of problem behavior from patterns of personality and perceived environment factors which antedate its occurrence.